Means for dressing grinding disks



April 5 A. RICKENMANN MEANS FORDRESSING GRINDING DISKS Fild Dec. 12, 1938 Patented Apr. 14, 1942 UNITED STATES PATENT omen I MEANS FOB IiBEZZEZ ZRH QDmG DISKS Q 7 i 7 Alfred Bickenmanm-Zurich, Switzerland, minor toleiahauer lool Works Limited. Zurich, Switzerland, a corporation of Switzerland Application December in Germany 3 Claims.

It is already well known to provide grinding wheels with a plurality of annular grooves, by means of which screw threads can be ground in August 2s, ms

(or. res-a1) work-pieces, say taps, stock dies and so on. It

is also known to form grooves in grinding wheels by means of trueing or pressure rollers, which are pressed against the rotating grinding wheel. The roller rolls on the periphery of the grinding wheel and forms grooves in the grinding wheel.

For grinding screw threads theaccurate pitch, uniformity of the profile and the diameter of the profile grooves of the grinding wheel are of considerable importance; As the grinding wheel is an exact replica of the trueing roller. it is therefore necessary to make the latter as accurate as possible. An important improvement in this respect is achieved by the method disclosed in the United States Patent No. 2,112,679. The method described in Patent No. 2,112,679 has the advantage'that the pressure roller .can be produced economically with the greatestpossible accuracy as it is ground as a single thread screw thread. @However it has the disadvantage that when used for profiling a multi-groove wheel it is not permanently in engagement with the sleeve.

The object of the present invention is a means which includes the advantages for the production of accurate disk tools according to Patent No. 2,112,679 but which at the same time enables the pressure rollers when profiling grinding wheels, to remain permanently in engagement with these. The means disclosed in Patent No. 2,112,679 for axially returning the roller after each revolution, instead of being used during profiling, are used when producing, that is to say when grinding the pressure roller. In this manner the pressure rollers are produced with an nular grooves. For grinding the pressure rollers, control means are provided which enable the cess. When the grinding wheel comes to lie in this recess the said axial movement can take place. The pressure roller istherefore provided as previously with a segmental recess and as compared with the device in Patent No. 2,112,679 there is so far not obtained any advantage but only the diflerence that the pressure roller instead of being provided with a spiral screw thread, has annular profile grooves. I

In order to eliminate the disadvantage of the recess, the pressure roller in accordance with the invention, is constructed of at least two coaxially divided parts, each of which is provided with a segmental recess.

when grinding the pressure roller, the parts of the said roller are so clamped on a mandrel that the segmental recesses of all the parts are located along the same straight line. When usingroller parts for profiling grinding wheels, the separate parts-however are so clamped on a mandrel that the segmental recesses are relatively turned to such an extent that always at least one part of the roller remainsin engagement with the grinding wheel so that the entire roller is operative with completely annular grooves. l

The invention further resides in the novel details of construction, combination and arrangechuck body, carrying the roller, to have imparted thereto an axial movement corresponding with the pitch of the screw thread to be ground, while however at the same time there is imparted to the roller itself a movement which is opposite to the pitch and the axial movement or the chuck body, so that the point of operation, that is to say the point of contact of the pressure roller and the grinding disk is not displaced in an axial direction. In order to obtain this result the pressure roller after each revolution of the said control means, must carry out an axial return movement opposite to the operating movement. This however is 'only possible when the pressure roller is provided with a segmental rement of parts, all of which will be first fully described in the following detailed description, and I then be particularly pointed out in the appended claims. reference being had to the accompanying drawing, in which:

Fig. 1 shows the pressureroller according to the first example of construction in the operative position, relatively to a pressure-roller grinding wheel.

Fig. 2 shows a part of the device for grindin the pressure roller.

Fig. 3 is a side elevation of the pressure roller.

Fig. 4 is an enlarged view of a detail of the grinding device.

The device may be used on a known grinding machine by means of which it is possible to grind screw threads with single ridged grinding wheels by the longitudinal grinding method. A grinding wheel i is mounted for rotation but non-axial movement, in the machine frame which is not shown. The drive is eflected positively by known gearing. The mandrel 2 is carried between centers 3 and t. The center 3 isassociated with the rotary tool spindlefi. The headstock 6 and the tailstock I are mounted on the slide 8 which is moved axially in accordance with the pitch in proportion to the rotation of the tool spindle 5.

ner by means of the leading screw and change wheels. The mandrel 2 is rotated by a dog 9. On the mandrel is mounted a non-rotatable, but axially movable sleeveii. The sleeve it itself supports a control cam if as also the roller l2 to be ground. This roller is shown axially divided into two parts in the present case. It consists of the parts I! and I2. By means of a nut it these parts arepressed against the collar ill of the sleeve III.

.The two parts i2 and E2 of the roller are provided with a segmental recess it. The roller part i2 is also provided with the wedge track i5 and I5. When grinding the roller the parts l2, l2 are so clamped on the mandrel that the segmental recesses I4 are located along a straight line. To the center 4 of the tailstock there is secured a holder IS. The mandrel 2 carries on the right hand side a sleeve II. with a groove ll of the sleeve I1 there engages the dog it of the holder "5. The sleeve I! is consequently prevented from rotating. To this sleeve is keyed a counter-cam i8 for the control cam ll. Between these cams are mounted balls 23. At the left hand end the mandrel carries an abutment "ring l9. Between this abutment ring and the sleeve I 0 is provided a spring which causes the cam Ii to be pressed towards the cam It.

When the mandrel 2 is rotated by the dog 9 then the roller parts l2, l2 also rotate with the control cam H. In accordance with the adjusted pitch the slide 8 moves in an axial direction and consequently there are moved correspondingly,

' the tail stock I, the head stock 6 and the mandrel 2. Assuming that it moves towards the right then the control cams Ii and I! must be so constructed that the roller parts I! and I! move axially towards the left relatively to the mandrel 2 according to the pitch. This movement takes place because the cam It remains stationary while the cam il rotates. The shape of the profile of the roller thus remains stationary relatively to the pressure-roller grinding wheel I which has been brought into contact with the roller, that is to say a closed annular groove is ground. After each revolution of the roller parts l2, l2 and the cam ii there occurs an axial return movement of the sleeve Ill when the point M of the cam H has reached the point 22 of the cam i8. This return movement must be completed at the moment at which the grinding wheel ll' passes through the segmental recess It. In other words. the grinding wheel I on the second rotation of the roller, engages with a secon groove of the' roller parts l2, l2. 1

The balls 23 located between the two cam surfaces are guided by the ball cage ring 2.

The arrangement of the holder for the counter cam l8, described and illustrated, permits of a convenient clamping and re-clamping of the en- 2,279,523 This movement is effected in the known man- A portion of the present invention resides therein that these intersecting grooves are arranged at an entirely optional irregular spacing. Fig. 1 shows diagrammatically how the roller parts l2, I! are used for the production of a multi-groove grinding disk 8. The roller parts It and I! are clamped in position relatively displaced so that always one of the two roller parts I: or IE remains in engagement with the disk 8. This grinding disk is in operative contact with a cutter or the like rotatably arranged on an axis indicated by line A-A.

A reduction of the speed of the roller parts l2, l2 and the re-acceleration of any one also as a consequence thereof does, consequently, not occur whereby a long life of the tools is obtained.

In the roller tool, as shown in Figs. 1 to 4, there are a minimum of two disks l2 and I2. Each disk, furthermore, is provided with an axial slot or groove It and It. The two disks or rollers l2,

l2 may be disposed on the common drive shaft in such manner that the grooves l4, M are angularly offset relatively to each other. They are shown mounted onthe same shaft in Fig. 2, and the grooves are shown offset in Fig. 1. The rollers or disks {2, I? may, however, also be secured on the same shaft in such manner that the grooves I 4, H are ,in alignment, so that the assembly of rollers l2, l2 has a groove extending from one end to the other.

In producing these roller tools, the process described in the prior Patent No. 2,112,679 may be &

tel

used. This means that for making the roller assembly i2, i2 a grinding disk l, as shown in Fig. 2, may be employed. This grinding disk operates in a way which is known'initself. As shown in Fig. 2 disk 'I always rotates in the same plane. The carriage 8 moves in the direction of one side and a distance equal to the distance of the annular tooth grooves on the rollers l2, and owing to the cam arrangement ll, i8, 2i, 22, Fig. 4, the part to be finished, namely, the assembly of rollers I2, I! is moved in the opposite direction. exactly the same distance, that is, opposite to the direction of the carriage 8. In this manner there are produced annular grooves in the roller assembly l2, I2. After each complete revolution, however, the disk I may be slid in the groove I 4, M which is then in alignment therewith. The feed of the carriage 8 and the dimensions of the cam groove on the parts 8, li must, therefore, correspond accurately with the space of the grooves on the rollers l2, l2. This manner of producing the annular grooves is known in itself. The novelty resides in thefact that subsequently, namely, after the the annular grooves on the support III, II, l8, the parts l2, l2" are removed from this support or chuck and are secured to the spindle for these gessnre rollers in offset relation, as shown in During the production of the annular grooves in rollers l2, l2 the grooves l4, H are in alignment with each other, as has been repeatedly stated. A relative axial displacement of the pressure rollers l2, I! with respect to the disk,

ranged at regular-intervals there is the danger that they become noticeable on the profiled Fig. 2, may, therefore, take place. (Still, the pressure roller l2, l2. when adjusted as shown in Fig. 1, uninterruptedly remains in engagement with the grinding disk S to be produced whenever the assembly of roller parts I 2, I2 is utilized for this purpose.

What I wish to claim and secure by U. S. Letters Patent is: p

1. A grinding disk rotating on its axis, a rdproductlon of tatable pressure roller having a peripherally grooved cutting surface, means by virtue of which said roller may be brought into operative contact with said grinding disk, and means to keep the said roller and the said grinding disk in operative contact when profiling the grinding disk, thesaid means consisting of at least two coaxially divided parts, each of said parts provided with a segmental recess, the said recesses being arranged at such an angle to one another that during profiling of the grinding disk always one roller part remains in operative contact with the said grindins'disk.

2. A device for dressing grinding disks, com-' prising a plural-part rotatable pressure roller the parts of-which are co-axial and each has corresponding peripherally grooved cutting surfaces provided with a recess, the several parts of the roller being secured together asa unit with the respective recesses staggered.

3. In combination with a grinding disk, 9. pressure roller therefor comprising an arbor, a pinralitv of disk-like roller elements secured together on said arbor, each disk-like element hav-. ing an axially disposed recess, the recesses of the several disk-like elements being staggered with respect to one another by virtue of all of which the recesses will clear the grindings without disengagement of the whole face of the pressure roller from the grinding disk. 

